1. Field of the Invention
The present invention generally relates to an image display technique, and more particularly, to an image-driving method and a driving circuit of a display.
2. Description of Related Art
In recent years, how to improve the blur motion image of a liquid crystal display (LCD) has become one of concerned issues of the relevant manufacturers. The problem of blur motion image is caused by slow response speed of liquid crystal molecules and the employed hold-type driving scheme in a display. To effectively overcome the problem of slow response speed, an over-drive technique was provided in the prior art. The conventional hold-type driving scheme has been continuously developed in two directions of impulsive drive scheme and motion estimation and compensation scheme. However, no matter of the over-drive technique, impulsive drive scheme or motion estimation and compensation scheme, a large memory capacity is required for tremendous accesses. In addition, if an architecture combines two of the above-mentioned schemes, the display needs a large bandwidth and a huge capacity of the employed memory.
FIG. 1 is a diagram showing an impulsive drive mechanism. Referring to FIG. 1, the adopted impulsive drive mechanism needs to insert a darker image between two original images, wherein the darker image is obtained by conducting a Gamma correction with a darker Gamma curve 100 instead of the regular and desired Gamma curve 104 on the original image. In addition, another brighter image is also required, wherein the brighter image is obtained by conducting a Gamma correction with a brighter Gamma curve 102 on the original image. As a result, the average luminance of the above-mentioned two images is close to the desired luminance, but the insertion of a dark frame gains the effect of impulsive drive and improves the blur motion image. The scheme is also termed as double-Gamma algorithm.
FIG. 2 is a diagram of a conventional image driving circuit to implement the impulsive drive mechanism. Referring to FIG. 2, image frame data are input into a frame doubler 106 in a rate of 60 Hz, and the input data are registered in the memory of a frame buffer 108. Then, the frame doubler 106 reads out the image data from the frame buffer 108 in a double rate of the above-mentioned input rate, i.e., 120 Hz. In other words, a present image is written into the frame buffer 108 in 16 ms duration or 60 Hz rate. Prior to writing the present image, the previous image is read twice out in 120 Hz rate. One of the read out images is sent to a dark-processing unit 110 for conducting a luminance adjustment based on a dark Gamma curve and then being output, while another of the read out images is sent to a bright-processing unit 112 for conducting a luminance adjustment based on a bright Gamma curve and being output to display. In this way, the frame frequency is updated from 60 Hz to 120 Hz, in which the two images are read out for conducting the dark and bright Gamma corrections, thus, the above-mentioned procedure is called the double-Gamma algorithm.
FIG. 3 is a diagram of a conventional image-driving method. Referring to FIG. 3, a frame 114 and another frame 120, i.e., two original frames 0 and 1, are sequentially input in 16 ms duration and stored in a frame buffer. Since an image is composed of, for example, 900 scan lines; thus, each of the sequentially input in 60 Hz rate present images is respectively represented by original frames 0, 1 . . . and each original frame includes data corresponding to the 900 scan lines. The frames 116, 118, 122 and 124 are images read out in 120 Hz rate and processed by luminance adjustments. Taking the original frame 114 as an example, the corresponding original frame 0 is read out twice from the frame buffer to get two image frames 116 and 118, wherein the frames are read out from the frame buffer one by one and then Gamma corrections with a bright Gamma curve and a dark Gamma curve are alternately and respectively conducted on the read out frames to obtain a bright frame 0 and a dark frame 0 for displaying. It can be seen from the above mentioned that the next image, i.e. the original frame 1, can be read only after completely reading out the previous original frame 0. Therefore, the circuit architecture must allow a whole image to be registered in the frame buffer until the registered image is read out twice to inputting the following original image, therefore, the conventional image-driving method has a lower operation efficiency.
In short, how to effectively solve the problem with a conventional display, for example an LCD, requiring excessive access bandwidth and memory capacity is still a significant development task for the relevant manufactures.